1. Field of the Invention
The present invention relates to a battery system including a battery pack group, each including battery packs connected in parallel.
2. Description of the Related Art
Recently, a power generation technology using natural energy (renewable energy) such as wind and solar ray has attracted attention. Further, a technology called a smart grid (next generation grid) also has attracted attention as a technology for stabilizing the grid, the smart grid operating a grid for connection, for example, in a mesh manner between a power plant and customers efficiently using IT (Information Technology).
In the grid, there may be an accident in the grid due to, for example, unbalance between the demands and supply of power. To previously prevent a power failure due to the accident in the grid, a battery system is used which includes battery packs each including single cells or assembled batteries connected in series. Out of such battery systems, there may be a battery system capable of outputting a power of a mega-watt class by combining a plurality of battery packs as a battery pack group, in which case, each of the battery packs should be supervised. Regarding the method of supervision, JP 06-283210 A discloses a mechanism for disconnecting one of battery packs having an error is disconnected from the body of the battery packs.
JP 06.283210 A discloses disconnection of the battery pack having an accident from the battery pack group by detecting an error state.
An aspect of the present invention provides a battery system comprising:
a plurality of battery packs connected in parallel each including a switch and a battery connected to the switch in series;
a battery state determining unit determining a state of the battery; wherein the battery state determining unit including:
a disconnection determining unit controlling disconnection of the switch and a switch controller controlling open and close of the switch in accordance with a result of determining the state, wherein
the disconnection determining unit calculates allowable stop period and demanded stop period of the battery packs on the basis of the past time-base data of charging and discharging, season data, and allowable currents of the battery and transmits data to the switch controller when the demanded stop period is smaller than the allowable stop period, and the switch controller makes the switch in an open state.